<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="https://code.jquery.com/jquery-3.6.4.min.js" integrity="sha256-oP6HI9z1XaZNBrJURtCoUT5SUnxFr8s3BzRl+cbzUq8=" crossorigin="anonymous"></script>
    <script>
        $(function () {
            var $div=$("div");
            // alert($div.html());
            // $div.html("我是div标签 <span style='background-color: orange'>我是div标签里面的span标签</span>");
            // alert($div.text());
            // $div.text("我是div标签 <span style='background-color: orange'>我是div标签里面的span标签</span>");
            // var $username=$("#username");
            // $username.val(12345678);
            // alert($username.val());
            // $(":radio").val(["3"]);
            // $(":checkbox").val(["1","3"]);
            // $("#hh,:checkbox").val(["3","4","3x","2x"]);
            //alert($(":radio:first").attr("name"));
            // $(":radio:first").attr("name","notradio");
            $(":radio:first").attr("abc","abcvalue");
        });
    </script>
</head>
<body>
    <div style="border: 1px solid">我是div标签 <span>我是div标签里面的span标签</span></div>
    <input type="text" name="username" id="username">
    <form>
        <input type="radio" name="radio" value="1">1
        <input type="radio" name="radio" value="2">2
        <input type="radio" name="radio" value="3">3
        <input type="checkbox" name="box" value="1x">cxk1
        <input type="checkbox" name="box" value="2x">cxk2
        <input type="checkbox" name="box" value="3x">cxk3
        <select id="hh" multiple="multiple">
            <option value="1">1</option>
            <option value="2">2</option>
            <option value="3">3</option>
            <option value="4">4</option>
        </select>
    </form>
</body>
</html>